The present invention relates to an apparatus for producing a conical sleeve for a cup and/or a conical paper cup having a machine frame and at least two star wheels which are rotatably connected with the machine frame and which are driveable in synchronized cycles, whereby the first star wheel comprises a number of conical mandrels, on each of which a sleeve can be formed from a flat-lying blank.
An apparatus of this type is prior art in International Patent Application WO 99/11526 A1. The construction of the known apparatus is very complicated and convoluted. The star wheels have differently arranged rotary axes, which are placed perpendicular to one another. The star wheels are also placed in different planes. Because of this, the transfer of the sleeve or of the paper cup from one star wheel to another is difficult. In addition, it is also difficult for a machine operator to access the processing stations on the star wheels. A conversion of the apparatus to another cup format is very complicated. Furthermore, access to the drives is poor, as the drives are mounted below the star wheels having vertically arranged drive shafts.
It is an object of the present invention to improve an apparatus of the above mentioned type.
This object has been achieved in accordance with the present invention in that the star wheels are disposed in one plane and are arranged to a vertical wall of the machine frame by means of horizontal drive shafts.
An arrangement of the star wheels such as this in the apparatus permits very good accessibility to the individual processing stations on the star wheels. A machine operator can view all star wheels very easily and can easily eliminate any faults which may occur.
The star wheels are advantageously connected to at least one drive, whereby the drive is arranged to the central wall of the machine frame on the side facing away from the star wheels. This has the advantage in that the drives are also very easily accessible from the back side of the machine in the case of operational failure. The drives can be very simply designed and are at the same time precise, as there are only short paths from the drive to the star wheel. In order to achieve the presently required cyclical speed of the machine of over 250 cycles per minute with good positional exactness of the star wheels, a very rigid and stable machine frame and drive construction is necessary due to the high accelerations and the mass inertia forces arising therefrom. The central wall of the machine frame guarantees a high level of stability and rigidity.
Sufficient space also exists on the back side of the machine to take up drives, which inevitably have relatively large dimensions due to the mass inertia forces. In contrast to the above mentioned prior art, where available space below the star wheel, which is arranged with a vertical axis of rotation, is limited, the space for the drives in the case of the present invention is not limited, as the position and accessibility of the star wheels is totally independent of the size of the drive.
At the same time, a very high level of precision of the production apparatus can be achieved by means of the central wall of the machine frame, as the central wall provides the assembly positions of the drives, the star wheels and the processing stations. No further frame parts are necessary, which impair the exactness with additional tolerances. The central wall of the machine frame can for example be made as a one-piece cast part, which can be machined completely on one machine tool, so that all bore holes and supporting surfaces possess a high level of positional accuracy in relation to one another.
The drives can be designed differently. For a very high level of rigidity and stability, for example, so-called indexing gear boxes are advantageous, in which a continuous rotational motion of a drive motor is converted into a cyclical rotational motion of the star wheel via a worm shaft having a changing pitch. It can also be advantageous to position the rotational axes of the drives parallel to the rotational axes of the drive shafts of the star wheels. A deflection of the rotational direction is then no longer necessary.
Advantageously the star wheels are fixed to the machine frame in a way which permits easy replacement of the wheels. For this purpose, easily releaseable means for connection with the drive, for example quick-action connectors, are provided. The apparatus can thus be converted very quickly to another cup format. For example a complete star wheel can be removed from the apparatus in very little time and be replaced by a star wheel prepared for a different cup format. Production loss during conversion of the machine is hereby minimised.
The apparatus according to the present invention is suited for manufacturing various types of cup, which can have round or optional shaped cross-sections. For example, one-walled paper cups from coated or uncoated paper or paperboard can be produced. A thin plastic layer is particularly suitable as a coating, which renders the paper material liquid-tight and which can be applied to one or both sides of the paper material. The arrangement according to the present invention is also very well suited for producing conical sleeves for various types of cup. The sleeves are formed from a pre-cut blank, for example of paper or paperboard, in that they are wound around a conical mandrel and joined together along their longitudinal side. The manufactured sleeves can for example form the outer sleeve of double-walled insulated cups or of plastic cups. They can also be placed in an injection mould to form the outer sleeve surface of a plastic cup. The plastic cup can hereby consist for example of a foamed plastic material.
The joining of the individual parts of the cup can take place in a variety of ways and is dependent on the types of material being joined and the requirements. Joining can for example take place by means of hot sealing, gluing with hot or cold glue or also by means of hot-melt-adhesives. When in the case of the present invention the word “joining” is mentioned, it always refers to any one of the above mentioned possibilities.
A separating device for feeding single blanks from a stack of blanks is assigned to the first star wheel of the apparatus is. The individual blanks are placed around the conical mandrel of the first star wheel and form thus a sleeve for a cup or directly the wall of a paper cup. When the blank is to form the wall of a paper cup, for example a one-walled paper cup or an inner cup for a double-walled insulating cup, it is advantageous to place to the first star wheel a device for forming a cup bottom, for example in the form of a bottom press, which feeds pre-formed cup bottoms to the mandrels of the first star wheel, which cup bottoms then are joined to the sleeve formed on the mandrel.
It is advantageous that the first star wheel is arranged to a second star wheel, which comprises a number of hollow mandrels, the insides of which can take up the paper cups and/or the formed sleeves. This causes the rim at end of the sleeve with the larger diameter to become freely accessible and this edge can then be processed according to requirements, for example an outwardly formed lip or a shoulder can be provided. The star wheels are arranged to one another in such a way that the paper cup and/or the sleeve can be transferred in a linear movement directly from one star wheel to the next star wheel. The transfer device can be very simply designed, for example by means of a simple blower nozzle. The simple linear movement over a short distance permits a reliable transfer even at high cycle rates.
In an embodiment of the present invention, the arrangement is particularly suitable for manufacturing a double-walled insulating cup made of paper or paperboard. Advantageously at least three star wheels are provided for the purpose. On the first star wheel, a sleeve is formed from a flat-lying blank, which sleeve is then transferred to the second star wheel. The third star wheel takes up pre-formed paper cups, in which a sleeve is already securely adhered to a bottom, for example from a cup magazine or direct from another cup-manufacturing machine. A cup magazine can also be provided as an intermediate storage device in the case of a cup-manufacturing machine arranged upstream thereof. A forming device for a means for stacking can be arranged to this third star wheel. The forming device forms a means for stacking, for example a bead or a shoulder in the sleeve of the paper cup. The paper cup is transferred from the third star wheel to the second star wheel and inserted in the sleeve and joined thereto. After the last processing station of the second star wheel a double-walled paper cup has been formed which possesses good insulating properties.
In an alternative embodiment of the present invention, the third star wheel can be used for feeding a finished plastic cup from a cup magazine. On the first star wheel a sleeve is in turn formed from paper material, where it can also be alternatively provided with a bottom, and transferred to the second star wheel. The plastic inner cup is transferred from the third star wheel to the second star wheel and inserted hereby into the paper outer sleeve or the outer cup.
In a further embodiment of the present invention a fourth star wheel can be provided, which is arranged downstream of the second star wheel and which again comprises conical mandrels, on which the double-walled cup, provided with the sleeve, is taken up. In the processing stations arranged to the fourth star wheel, finishing work can be carried out, for example in the area of the paper cup in which the bottom is secured, for example in order to improve the design or the stacking properties of the cup. The stacking properties of the double-walled cup can for example be improved in that the area of a skirt is radially widened in a processing station of the fourth star wheel.